JPS6281663A - Copying machine - Google Patents

Abstract

PURPOSE:To shorten time of copying work by not making preliminary scanning when it is judged that the original is not replaced and leaving the exposure level determined previously at it is. CONSTITUTION:An automatic density control mode is set by setting an AE key. In the case where an automatic density setting mode is set, preliminary scanning is made when the flag is set to '1', and when the flag is '0', copying operation is made. The flag is set to '1' when an original cover 28 is opened, and set to '0' when preliminary scanning is made. Then, copying operation of set number of sheets is executed. On the other hand, when the cover 28 is not opened, it is judged that the original is not replaced and preliminary scanning is not made, the exposure level determined in previous time is kept as it is. Consequently, preliminary scanning is eliminated when additional copying is made for the same original, and copying work can be performed in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copying machine, and more specifically, it measures the image density of a document by performing a preliminary scan prior to a copying operation. The present invention relates to a copying machine equipped with an automatic density control mechanism that changes an image density control level.

Conventional Technology In recent years, copying machines have been equipped with automatic density control mechanisms that control exposure and developing bias voltage, etc. according to the image and color condition of the original to automatically obtain an appropriate copy image density. something suggested or offered.

Problems to be Solved by the Invention In such a copying machine, when the print switch is pressed, a preliminary scan (hereinafter referred to as prescan) is performed prior to copying, and the image density of the original is measured. The image density control level was determined and the exposure amount, developing bias voltage, etc. were controlled.For this reason, for example, after making a trial copy of one sheet, setting the required number of copies, and pressing the print switch again to make copies. In such cases, pre-scanning is required both when making a trial copy and when making the required number of copies, even though the exposure conditions have not changed, resulting in the inconvenience that copying takes time. In view of the above-mentioned circumstances, the present invention has been devised to provide an automated system that can perform copying work in a short time without having to perform prescanning multiple times as long as there are no changes to the exposure conditions when additional copies are made to the same document. The purpose is to provide a concentration control mechanism.

Means for Solving the Problems In order to solve the above problems, the image density of the original is detected by performing a preliminary scan prior to the copying operation, and the image density of the copy is determined based on this detection result. A copying machine equipped with an automatic density control mechanism that varies a control level includes a detection means for detecting that an original has been replaced, and a detection means for detecting that the original has been replaced after a series of copying operations has been completed. When the next copy is to be made in a state where there is no image density, the preliminary scan is not performed and the copy is made according to the previous image density control level.

Function: If the detection means for detecting that the original on the document table glass of the copying machine has not detected that the original has been replaced, this function is used to detect the density of the original image prior to the copying operation. A copying operation is performed at the previous image density control level without performing a preliminary scan.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a copying machine schematically showing the configuration of a copying machine (11).A photosensitive drum σ0 is supported at approximately the center of the main body of the copying machine so as to be rotatable in a counterclockwise direction. , around it are an erase lamp (11), a charging charger (121), a developing device (13), and a transfer charger +1.
41, a separation charger (15), a cleaning device (10, etc.) are arranged in this order.

In the scanning optical system (3), the exposure lamp (21) and the first scanning mirror 122 move integrally to the left in the figure.
2nd at a speed of /2. By similarly moving to the left of the third scanning mirror, the original held between the original platen glass 129) and the original cover 28+ is scanned, and the original is scanned through the imaging lens +251 and the fixed mirror ■. , an original image is projected onto a rotating photoreceptor drum (101).

A toner image corresponding to the original image is formed on the surface of the photoreceptor drum [10] by passing through the steps of charging two images, exposure and development, and this toner image is transferred to the transfer charger (14).
One portion of the image is transferred onto a copy sheet that is conveyed in synchronization with the image forming operation by the paper feed roller f311, timing roller (2), etc. of the copy paper conveyance system.

The copy paper that has passed the transfer process is transferred to a separation charger (15)
The image is separated from the surface of the photoreceptor drum (10) by the fixing roller (33), and then transferred to the tray (31).
1 and the copying is completed.

In the above copying operation, it is well known that the light intensity of the exposure lamp (2υ) or the developing bias in the developing device (13i) affects the density of the copied image. , is equipped with a mechanism (manual density control) for making the emission intensity of the lamp (2I) variable by external operation and adjusting the density of the copied image.

On the other hand, it is known that even with the same light intensity and developing bias, there are differences in the quality of the copied image, especially in the density of the copied image, depending on the condition of the original image, the quality of the paper, and one color difference. , the copying machine of the present invention (11) further detects the intensity of reflected light from the document surface using a light-receiving element (see FIG. 2) regarding the image condition, paper quality, one color, etc. of these documents, and converts it into a detected value. Correspondingly, the lamp (
21) is equipped with a mechanism (automatic density control) that controls the light emission intensity to make the density of the copied image constant.

FIG. 2 is a plan view schematically showing an example of the arrangement of light-receiving elements used for automatic density control. The reflected light is received, and the output level varies depending on the detected intensity.

FIG. 3 shows the main parts of the operation panel group of the copying machine (1). The automatic concentration control mode is set by operating the AE main key 51J, and the automatic display ■ lights up.

The manual density control mode is set by pressing the AE main key 51) again, and at this time the auto display ■ or goes out, and the light intensity increase (UP) key (curse) or light intensity decrease (DN
) By operating the key (2), one of the concentration displays (55) in the manual control mode lights up, and the light intensity of the lamp (21) is controlled at the concentration level indicated thereby.

FIG. 4 is a circuit diagram showing the relationship between the microcomputer system that controls the operation of the copying machine 11 and the image density, etc., and the light emitting diodes for displaying the various input switches 2.

Input port (P5) of microcomputer (100)
~ (P8), AE main key 51) on the operation panel mark)
, the switches (SWI) and (SW2) corresponding to the UP key (53) and the DN key (54), respectively.
, (!1iVv3) and a switch (5vv4) that detects opening and closing of the document cover to determine whether to replace the document.
are connected to the output ports (PA) to (PD), and a light emitting diode (L
EDI) to (LED5) are connected, and the current limiting resistor (
A light emitting diode (LED5) for automatic density control display is connected via R26).

Output port (PE) of microcomputer (100)
~(1) I) is connected to a phase control circuit (103) via a driver (102) and resistors (R21) to (R25) for setting the light level, and the phase control circuit (103)
Further, the output of the above-mentioned light receiving element - is inputted to +.

The phase control circuit (103) triggers the switching element (104) via a pulse transformer (pT), and the trigger triggers the lamp (2) depending on the timing.
control the amount of light.

In this control, in the automatic density control mode, the phase control circuit (103) operates to automatically control the light amount so that the output of the light receiving element port reaches a predetermined target value level, and in the manual density control mode, the phase control circuit (103) operates to automatically control the light amount. Resistor used (R21
) to (R25), the light emission is controlled at a fixed control phase level determined by (R25).

The output of the phase control circuit (103) is also output from the A/D converter (103).
The input ports (Pl) to (P4) of the microcomputer (100) are input through the microcomputer (100) through the
The exposure control level is determined when a timing signal is output from the PK), and the control level when the automatic density control mode is executed is thereby displayed.

The control processing procedure executed by the microcomputer (100) will be described below with reference to the flowchart shown in FIG.

In FIG. 5, in step #1, initialization processing of the memory, registers, flags, etc. in the microcomputer (100) is executed when the power is turned on. Step #2
is a process of presetting predetermined data for control variable items of the copying machine (1), for example, the number of copies - 1,
Initial settings such as copy magnification - same size and paper feed section = upper stage are performed. In step #3, it is determined whether or not the print switch has been pressed. If it has been pressed, the process proceeds to step #4; if it has not been pressed, the process skips steps #4 to #9 and proceeds to step #10. In step #4, it is determined whether or not the AE mode is selected using the aforementioned AE primary key 51). If the AE mode is selected, the process proceeds to step #5; if the AE mode is not selected, the process proceeds to step #5. is the UP key (Kasumi or D) mentioned in step #7
The exposure level is determined according to the density level set with the N key. In step #5, the flag (FCO
If the flag (FCOVER ) is step #11, which will be described later.
This flag is set to ``■'' when the document cover (28) is opened, and is reset to ``0'' when the prescan operation is performed in step #6.Step #
In step 6, a prescan is performed prior to the copy operation, the data obtained by this prescan is held, and processing for determining the exposure level is executed, and the flag (FCOVER) is reset to "O".

In step #8, a copying operation is performed until it is determined in step #9 that the set number of copies have been completed.

Note that the specific copying operation is already well known, so it will not be described in detail here. In step #10, it is determined whether the document holder has been opened. If the document cover example has been opened, the process proceeds to step #11; if the document cover has not been opened, the process returns to step #3. Switch (SW4) determines whether the document cover (28) is opened or not.
Detected by 0N10FF. In step #11, the flag (FCOVER) is set to "1", the sample data held in step #6 is cleared, and the process returns to step #3.

As described above, in this embodiment, when the document holder is opened, it is determined that the document has been replaced, and a pre-scan is performed prior to the copying operation, exposure is performed, and the bell is automatically set. If the document holder is not opened, it is determined that the document has not been replaced, and no prescanning is performed, leaving the previously determined exposure level unchanged. For this reason,
When making additional copies of the same document, pre-scanning is not performed multiple times, and the copying work can be completed in a short time.

Further, a changeover switch may be used to switch between the AE mode of the present invention in which prescanning is not performed when the document is replaced, and the conventional AE mode in which prescanning is performed whenever the print switch is pressed. For example, if the AE mode is specified with the AE main key +511 shown in Fig. 3 and the changeover switch is ON, the AE mode will be set as described above. When OFF, the conventional AE mode is used. Figure 6 is a chart 70 showing the processing when a changeover switch is provided in this way, and it is determined whether the changeover switch is turned down between step #4 and step #5 of the chart 70 shown in Figure 5. It is sufficient to provide step #4'.

Furthermore, in the above embodiment, a switch (SW4) that detects opening and closing of the document cover (support) is used as a detection means for detecting that the document has been replaced, but a photo sensor is installed below the document table glass. In a copying machine using a document feeder (DF), detection may be performed by driving a conveyor belt that conveys the document.

Further, in the above embodiments, the image density is controlled by controlling the voltage of the exposure lamp, but the image density may be controlled by controlling the voltage of the developing bias.

Effects of the Invention As is clear from the above explanation, in the present invention, the image density of the original is detected by performing a preliminary scan prior to the copying operation, and the image density control level for copying is varied based on this detection result. A copying machine equipped with an automatic density control mechanism that detects whether the original has been replaced, and a detection means that detects that the original has been replaced, and a copying machine that detects whether the original has been replaced after a series of copying operations has been completed, and when the original has not been detected by the detection means that the original has been replaced. When copying is performed, the above-mentioned preliminary scanning is not performed and the copying is performed according to the previous image density control level, so that when additional copying is to be performed on the same original. If there is no change in the exposure conditions, the copying operation time can be shortened without performing pre-scanning multiple times.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a copying machine schematically showing the configuration of the copying machine;
Fig. 2 is a plan view schematically showing the arrangement of light receiving elements used for automatic density control, Fig. 3 is a diagram showing the main parts of the copying machine, Fig. 4 is a control circuit diagram of the copying machine, and Fig. 5 is a diagram showing the main parts of the copying machine. FIG. 6 is chart 70 showing the processing procedure for controlling the copying machine according to the present invention. FIG. 6 is chart 70 showing the processing procedure for controlling the copying machine according to another embodiment. (11... Copy machine, ■... Original cover, 6D.
...AE primary key (cpu)...microprocessor. Applicant Minolta Camera Co., Ltd. Figure 5 Figure b

Claims (1)

[Claims] A copying machine equipped with an automatic density control mechanism that detects the image density of a document by performing a preliminary scan prior to a copying operation, and changes the image density control level for copying based on the detection result. The machine includes a detecting means for detecting that the original has been replaced, and a detecting means for detecting that the original has been replaced. 1. A copying machine comprising: control means for copying based on a previous image density control level without performing regular scanning.